As the first half of its Bison I wind project in North Dakota nears completion, Minnesota Power is shifting into 2011's second phase by upgrading to more efficient, new direct-drive turbines.
For the second phase of its first wind energy project in North Dakota, the Duluth, Minn.-based division of ALLETE Inc. will install 15 new 3 MW turbines manufactured by Siemens instead of the 17 turbines of 2.3 MW originally planned. The new turbine arrangement is expected to generate an additional 10,000 MWh of annual energy.
The SWT-3.0-101 direct-drive wind turbines feature a permanent magnet generator but no gearbox. With the number of parts in the turbine reduced by half, the direct-drive technology has the potential to reduce maintenance time, resulting in higher turbine availability, according to Minnesota Power.
Minnesota Power, Siemens and other contractors have been working since this spring on the first phase of Bison I, located in west-central North Dakota. Major components began arriving on the worksite in September, and the last of the Phase I turbine structures were erected in mid-October. All 16 turbines in Bison I's first phase are now operational.
Renewable energy generated at the Bison project will be delivered to Minnesota Power's customers in northeastern Minnesota over a 465-mile direct-current transmission line that it purchased on Dec. 31, 2009.
SOURCE: Minnesota Power